Add rdkit as a pypi dep

[hadim]

Changelogs

• Add rdkit as a pypi dep. Now possible after the rdkit conda package fix at https://github.com/conda-forge/rdkit-feedstock/pull/143

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Checklist:

• [ ] Was this PR discussed in an issue? It is recommended to first discuss a new feature into a GitHub issue before opening a PR.
• [ ] Add tests to cover the fixed bug(s) or the new introduced feature(s) (if appropriate).
• [ ] Update the API documentation is a new function is added, or an existing one is deleted.
• [x] Write concise and explanatory changelogs below.
• [x] If possible, assign one of the following labels to the PR: feature, fix or test (or ask a maintainer to do it for you).

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discussion related to that PR

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (c23d273) 91.95% compared to head (714919a) 91.93%. Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #219 +/- ## ========================================== - Coverage 91.95% 91.93% -0.03% ========================================== Files 46 46 Lines 3843 3843 ========================================== - Hits 3534 3533 -1 - Misses 309 310 +1 ``` | [Flag](https://app.codecov.io/gh/datamol-io/datamol/pull/219/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datamol-io) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/datamol-io/datamol/pull/219/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datamol-io) | `91.93% <ø> (-0.03%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datamol-io#carryforward-flags-in-the-pull-request-comment) to find out more.

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